Place lentils in a large saucepan; cover with water 2 inches above lentils. Bring to a boil; cover, reduce heat, and simmer 25 to 30 minutes or until tender. Drain well; cool.
Bring broth to a boil in a medium saucepan; gradually stir in couscous. Remove from heat; cover and let stand 5 minutes. Fluff with a fork.
Combine lentils, couscous, bell pepper, and next 3 ingredients in a large bowl; stir gently.
Combine lemon juice and next 4 ingredients in a small bowl. Pour lemon juice mixture over couscous mixture; stir gently. Stir in cheese.